Cellulose powder

ABSTRACT

This cellulose powder has: an average degree of polymerization of 100 to 350; a weight average particle size of over 30 gm, but less than 250 μm; an apparent specific volume of 2 to less than 15 cm 3 /g; and an organic carbon content from residual impurities, which is defined by the total organic carbon content (%) during 1% NaOH extraction to the total organic carbon content (%) during pure water extraction, of over 0.07 to 0.3%.

TECHNICAL FIELD

The present invention relates to a cellulose powder used in pharmaceutical, food, and industrial applications. More specifically, the present invention relates to a cellulose having improved compression compactibility and high effects of improving flavor release from Kampo medicines or the like and coloring of sugar coated tablets or the like, and suitable for excipients for compression and granulation in applications of pharmaceuticals. The present invention also relates to molded articles comprising the cellulose.

BACKGROUND ART

Kampo medicines have been positively taken for improvement in health and prevention of disease in recent years. The unique bad odors of Kampo medicines cause difficulties and obstacles to the intake thereof.

Tablets containing Kampo medicines having bad odors have been coated with sugar to suppress the odors, or have been compounded with sweeteners to mask their bitterness.

Sweeteners, if compounded, undesirably increase the calories of Kampo medicines to be taken for prevention and improvements of diabetes, obesity, and the like. For this reason, methods of improving bad odors of Kampo medicines without compounding sweeteners have been required. The content per tablet of Kampo medicines is large, and a number of Kampo medicines are raw powders having large specific volumes. Such bulkiness limits the amount of an excipient for compression to be compounded, and as a result, tablets are readily worn. For this reason, an excipient for compression having high compression compactibility has been required.

Patent Literature 1 describes a formulation that can reduce the bad taste unique to Bofutsushosan by compounding a microcrystalline cellulose.

As an excipient to enhance compactibility, microcrystalline celluloses described in Patent Literatures 2 to 5 are known.

CITATION LIST Patent Literature

Patent Literature 1: JP 2009-242328 A

Patent Literature 2: JP 40-26274 B

Patent Literature 3: JP 56-2047 B

Patent Literature 4: International Publication No. WO2006/115198

Patent Literature 5: JP 57-212231 A

SUMMARY OF INVENTION Technical Problem

Unfortunately, the formulation described in Patent Literature 1 contains the microcrystalline cellulose described in Patent Literature 3, which is prepared by a method different from the method according to the present invention. The microcrystalline cellulose may have poor compactibility when the contents of main drugs are larger. As a result, satisfactory tablets cannot be always obtained. The formulation still has the odors of Kampo medicines. The formulations as sugar coated tablets undesirably reduce the whiteness of sugar coating layers. Patent Literature 2 describes a microcrystalline cellulose having an average degree of polymerization of 15 to 375, an apparent specific volume of 1.84 to 8.92 cm³/g, a particle size of 300 μm or less. Patent Literature 3 describes a microcrystalline cellulose having an average degree of polymerization of 60 to 375, an apparent specific volume of 1.6 to 3.1 cm³/g, an apparent dense specific volume of 1.40 cm³/g or more, 2 to 80% by weight particles of 200 mesh or more, and an angle of repose of 35 to 42°. Patent Literature 4 describes a porous cellulose aggregate having a secondary aggregation structure formed by aggregation of cellulose primary particles, having an intraparticle pore volume of 0.265 cm³/g to 2.625 cm³/g, containing I-type crystals, having an average particle size of more than 30 μm and 250 μm or less, a specific surface area of 0.1 m²/g or more and less than 20 m²/g, an angle of repose of 25° or more and less than 44°, a degree of swelling of 5% or more, and disintegration properties in water. Patent Literature 5 describes a method of preparing a cellulose powder in which a cellulose raw material composed of cellulose fibers having a diameter of 2 to 2.0 μm is hydrolyzed with mineral acid to prepare a depolymerized product having an average degree of polymerization of about 100 to 300, and the depolymerized product is cut into a specific shape in a liquid until the resulting product reaches the size so as to pass through a metallic mesh of about 60 mesh. These microcrystalline celluloses, which have configurations different from that of the cellulose powder according to the present invention, have poor compactibility, attain insufficient flavor release from Kampo medicines used in combination, or may reduce the whiteness of sugar coating layers in formation of sugar coated tablets.

An object of the present invention is to provide a cellulose powder having high compression compactibility, and improving flavor release from Kampo medicines or the like and coloring properties of sugar coating layers of sugar coated tablets.

Solution to Problem

The present inventors, who have conducted extensive research in consideration of such circumstances, have found that a cellulose powder having physical properties controlled to fall within specific ranges can improve not only compression compactibility but also flavor release from Kampo medicines or the like and coloring properties of sugar coating layers, and have achieved the present invention. Namely, the present invention is as follows.

-   (1) A cellulose powder having an average degree of polymerization of     100 to 350, a weight average particle size of more than 30 μm and     250 μm or less, an apparent specific volume of 2 to 15 cm³/g, and an     amount of organic carbon derived from residual impurities of more     than 0.07 and 0.3% or less, the amount of organic carbon derived     from residual impurities being defined by the expression: amount of     total organic carbon (%) during extraction with 1% NaOH−amount of     total organic carbon (%) during extraction with pure water. -   (2) The cellulose powder according to (1), wherein the apparent     specific volume is 2 to 6 cm³/g. -   (3) The cellulose powder according to (1), wherein the apparent     specific volume is 2 cm³/g or more and less than 4 cm³/g. -   (4) The cellulose powder according to any one of (1) to (3), wherein     an intraparticle pore volume is 0.1 cm³/g or more and less than     0.265 cm³/g. -   (5) The cellulose powder according to (1), wherein a water     absorption capacity is 1.8 to 4.0 cm³/g. -   (6) A molded article comprising the cellulose powder according to     any one of (1) to (5). -   (7) The molded article according to (6), wherein the molded article     is a tablet containing one or more active ingredients. -   (8) A method of preparing a cellulose powder, comprising:     hydrolyzing a natural cellulose substance at a hydrochloric acid     concentration of 0.05 to 0.3% at a hydrolysis temperature of 80 to     150° C. for a hydrolysis time of 40 to 150 minutes to control a     volume average particle size of particles in a cellulose dispersion     liquid after the hydrolysis to be 70 to 200 μm, and then spray     drying the resulting dispersion liquid to prepare a cellulose powder     having an average degree of polymerization of 100 to 350, a weight     average particle size of more than 30 μm and 250 μm or less, an     apparent specific volume of 2 to 15 cm³/g, and an amount of organic     carbon derived from residual impurities of more than 0.07 and 0.3%     or less, the amount of organic carbon derived from residual     impurities being defined by the expression: amount of total organic     carbon (%) during extraction with 1% NaOH−amount of total organic     carbon (%) during extraction with pure water. -   (9) A molded article including one or more active ingredients, one     or more additives selected from saccharides, sugar alcohols,     starches, and disintegrating agents, and a cellulose powder, wherein     the molded article has a hardness of 50 to 200 N, a tensile strength     of 0.1 to 12 MPa, a friability of 0 to 0.5%, a swelling rate of a     diameter of the molded article in acetone of 0 to 3.3% or less. -   (10) The molded article according to (9), comprising 5 to 90% by     weight of a cellulose powder. -   (11) The molded article according to (9) or (10), wherein an amount     of total organic carbon derived from residual impurities according     to molded article residues obtained through washing of the molded     article with acetone, ethanol, pure water, and ethanol sequentially     and extraction is more than 0.07 and 0.3% or less. -   (12) The molded article according to (9) or (10), wherein the amount     of total organic carbon derived from residual impurities in the     cellulose powder obtained through washing of the molded article with     acetone, ethanol, pure water, and ethanol sequentially and     extraction is more than 0.07 and is 0.3%.

Advantageous Effects of Invention

The cellulose powder according to the present invention has high compression compactibility and can improve flavor release from Kampo medicines or the like and the coloring properties of sugar coating layers of sugar coated tablets.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a diagram showing the relationship between the apparent specific volume and the hardness of the cellulose powder according to the present invention (Examples 1 to 4) and the conventional cellulose powder (Comparative Examples 1 and 2).

DESCRIPTION OF EMBODIMENTS

The present invention will now be described in more detail.

The cellulose powder according to the present invention has an average degree of polymerization of 100 to 350, preferably 150 to 300, more preferably 180 to 250. The average degree of polymerization of 100 or more is preferred because the compactibility is improved, and the average degree of polymerization of 350 or less is preferred because the powder has high fluidity and disintegration properties while fibrous properties are not demonstrated. Namely, an average degree of polymerization of 100 to 350 is preferred because it attains particularly well-balanced compactibility, disintegration properties, and fluidity.

The cellulose powder according to the present invention should have a weight average particle size of more than 30 μm and 250 μm or less. A weight average particle size of more than 30 μm improves handling without increasing adhering and aggregating properties, and attains high fluidity. A weight average particle size of 250 μm or less is preferred because such a size does not separate or segregate the cellulose powder from the active ingredient, and may not reduce the content uniformity of formulations. The weight average particle size is preferably more than 30 μm and 180 μm or less.

The cellulose powder according to the present invention should have an apparent specific volume of 2 to 15 cm³/g. The apparent specific volume is preferably 2 to 13 cm³/g, more preferably 2 to 6 cm³/g, particularly preferably 2 cm³/g or more and less than 4 cm³/g. An apparent specific volume of 2 cm³/g or more improves compactibility. The upper limit is at most 15 cm³/g because an apparent specific volume more than the upper limit restores elasticity due to fibrous properties. The upper limit is preferably 6 cm³/g or less, more preferably less than 4 cm³/g because fluidity and disintegration properties are improved. The apparent specific volume is preferably 2.3 to 3.8 cm³/g, particularly preferably 3.0 to 3.8 cm³/g.

The cellulose powder according to the present invention preferably has an apparent tapping density of 0.2 to 0.6 g/cm³. The apparent tapping density is more preferably 0.3 to 0.58 g/cm³, particularly preferably 0.35 to 0.55 g/cm³. When an apparent tapping density is 0.6 g/cm³ or less, compactibility is improved.

The cellulose powder according to the present invention preferably has an angle of repose of 36° or more and less than 44° as an index of fluidity of the powder from the viewpoint of the content uniformity. The angle of repose is more preferably 38° to 42°.

The cellulose powder according to the present invention preferably has an intraparticle pore volume of substantially zero. The value of the intraparticle pore volume determined by the method according to WO2006/115198 is preferably 0.1 cm³/g or more and less than 0.265 cm³/g. If the particles have substantially no inner pores, flavor release can be improved without adsorbing even flavors with good smells, and thus this is preferable.

The cellulose powder according to the present invention should have an amount of organic carbon derived from impurities remaining in the cellulose raw material of more than 0.07 and 0.3% or less. The amount is preferably more than 0.07 and 0.25%, more preferably 0.09 to 0.15%. In the present invention, the amount of organic carbon derived from residual impurities is defined by the difference (%) between the amount of total organic carbon (TOC) in 5 g of a cellulose powder extracted from the cellulose powder (5 g) with pure water (80 mL) and the amount of TOC in 5 g of a cellulose powder extracted from the cellulose powder (5 g) with an aqueous solution of 1% sodium hydroxide (80 mL). The amount of TOC extracted with the aqueous solution of 1% sodium hydroxide reflects the amounts of an alkali-soluble ingredient and a pure water-soluble ingredient contained in the cellulose powder. From the amount of TOC, the amount of TOC extracted with pure water, namely, the pure water-soluble ingredient is subtracted to determine the amount of the alkali-soluble ingredient in the cellulose powder. The value is correlated with the amount of organic carbon derived from residual impurities.

In the cellulose powder according to the present invention, the amount of organic carbon derived from residual impurities, which is defined in the present invention, is higher than that of the cellulose powder prepared by a conventional method. The organic carbon derived from residual impurities is an alkali-soluble ingredient slightly contained in the cellulose powder. Surprisingly, the present inventors have found that a larger amount of organic carbon derived from residual impurities leads to higher compression compactibility. The organic carbon derived from residual impurities, although slightly contained, is present on the surfaces of individual cellulose powder particles to enhance the adhesive force. If the amount of organic carbon derived from residual impurities is controlled to fall within the range specified in the present invention, compactibility is improved by 10 to 300%. The present inventors have also found that the ingredient slightly contained can contribute to an improvement in flavor release. This is probably because the organic carbon derived from residual impurities as defined in the present invention adsorbs ingredients having strong odors to increase the concentrations of flavors with good smells probably contained in natural products, and thus improves bad odors of ingredients. Furthermore, the present inventors have found that the organic carbon derived from residual impurities has emulsifying properties, which improves dispersibility in sugar. For this reason, when the cellulose powder is added to the sugar coating layer, the cellulose powder is entirely dispersed to enhance the coloring properties of the sugar coating layer.

If the amount of organic carbon derived from residual impurities is controlled within the range specified in the present invention, compression compactibility and improvements in flavor release and coloring properties of sugar coating layers can be demonstrated in a good balance.

The cellulose powder according to the present invention is prepared by hydrolyzing a natural cellulose substance under a condition where the acid concentration is lower than that in the conventional method. Namely, a natural cellulose substance is hydrolyzed at a hydrochloric acid concentration of 0.05 to 0.3° A at a reaction temperature of 80 to 150° C. for 40 to 150 minutes after the temperature reaches the predetermined reaction temperature. Thereby, impurities inside cellulose particles correlated with the amount of organic carbon derived from residual impurities extracted from cellulose particles with hot water during the hydrolysis can be reduced. After drying, the amount of organic carbon derived from residual impurities can be increased inside the cellulose particles. As a result, the flavor release effect is also improved. A concentration of hydrochloric acid of 0.05% or more is preferred because the amount of organic carbon derived from residual impurities inside the cellulose particles after drying is not significantly increased, and compression compactibility and disintegration properties in water are well balanced. The flavor release effect is also likely to be improved. A concentration of hydrochloric acid of 0.3% or less is preferred because the amount of organic carbon derived from residual impurities inside the cellulose particles after drying is increased, and the effects of improving flavor release, the coloring properties of sugar coating layers, and the like according to the present invention are attained. A preferred range of the concentration of hydrochloric acid is 0.08 to 0.25%, particularly preferably 0.08 to 0.15%. A preferred range of the reaction temperature is 100 to 150° C., and a preferred range of the reaction time is 70 to 110 minutes.

Stirring should be performed under the hydrolysis condition to control the volume average particle size of particles in the cellulose dispersion liquid after the hydrolysis to be 70 to 200 μm. Preferably, the volume average particle size of particles in the cellulose dispersion liquid after hydrolysis is 70 to 150 μm. Preferably, after dehydration of the cellulose dispersion liquid, the product is washed with pure water several times, and is neutralized with an alkali, and then the product is again dehydrated to prepare a cellulose cake having 20 to 50% by weight of solid content.

Preferably, in the cellulose powder according to the present invention, the cellulose cake is mixed with pure water to prepare a cellulose slurry having 10 to 25% by weight of solid content. It is preferable that the cellulose slurry is stirred or the like to control the volume average particle size of the particles in the cellulose dispersion liquid before drying to be 40 μm or more and less than 50 μm, and then is spray dried. A volume average particle size of 40 μm or more is preferred because the fluidity of the cellulose powder after drying is improved. A volume average particle size of less than 50 μm is preferred because fluidity without demonstrating fibrous properties is improved.

The spray drying temperature can be 150 to 300° C., which is an inlet temperature typically used.

Stirring during the reaction or a subsequent step can reduce the lengths of cellulose fibers. The volume average particle size of the particles can be reduced by a larger stirring force, and can be increased by a smaller stirring force. The stirring force can be properly adjusted so as to attain a desired volume average particle size to control the volume average particle size of the cellulose particle within the range specified in the present invention.

The stirring force can be adjusted by varying the size and shape of a stirring tank, the size and shape of a stirring blade, the number of rotations, the number of baffle plates, and the like.

After the reaction, the cellulose dispersion liquid is washed to adjust the pH. This obtained cellulose dispersion liquid before drying preferably has an electric conductivity (IC) of 200 μS/cm or less. When an IC is 200 μS/cm or less, the dispersibility of the particles in water and disintegration properties are improved. The IC is preferably 150 μS/cm or less, more preferably 100 μS/cm or less. The cellulose dispersion liquid can be prepared with water or water containing a small amount of an organic solvent in the range not to impair the effect of the present invention.

In the present invention, the natural cellulose substances indicate natural-derived vegetable fibrous substances containing cellulose such as wood materials, bamboo, cotton, and ramie, and preferably are substances having a crystal structure of cellulose I. From the viewpoint of yield in preparation, the natural cellulose substances are particularly preferably refined pulp products of these substances, which desirably contain 85% or more of α-cellulose.

The cellulose powder according to the present invention preferably has a water absorption capacity of 1.8 to 4.0 cm³/g. A water absorption capacity of 1.8 cm³/g or more is preferred because sugar coated tablets are difficult to bond, and compactibility is also improved. A water absorption capacity of 4.0 cm³/g or less is preferred because an increase in an amount of a liquid used for sugar coating does not impair drying efficiency. A water absorption capacity of 3.5 cm³/g or less is preferred because fibrous properties are barely demonstrated and fluidity and disintegration properties are high. The water absorption capacity is more preferably 1.8 to 3.0 cm³/g, particularly preferably 1.8 to 2.8 cm³/g.

In the present invention, the molded article indicates molded articles including the cellulose powder according to the present invention and properly prepared by a known method selected from mixing, stiffing, granulation, pressing, size regulation, drying, and the like. Examples of molded articles used in pharmaceuticals include solid formulations such as tablets, powder medicines, subtle granules, granule agents, liquid extracts, pills, encapsulated formulations, lozenges, and poultices. The molded article according to the present invention includes not only those used in pharmaceuticals but also those used in foods such as confections, health foods, texture improvers, and dietary fiber strengthening agents, cake make-ups, bath agents, medicines for animals, diagnostic agents, pesticides, fertilizers, ceramic catalysts, and the like.

In the present invention, the molded article may comprise the cellulose powder according to the present invention in any content. The content is preferably 1 to 99.9% by weight based on the weight of the molded article. A content of 1% by weight or more can prevent abrasive wear or breakage of the molded article to give sufficient physical properties. The content is preferably 3% by weight or more, preferably 5% by weight or more. The upper limit of the content of the cellulose powder is 99.9% by weight or less, more preferably 90% by weight or less from the viewpoint of efficacies of active ingredients.

Furthermore, in the present invention, the molded article may contain, in addition to the cellulose powder according to the present invention, optionally other additives such as active ingredients, disintegrating agents, binders, fluidizing agents, lubricants, flavoring substances, fragrances, colorants, sweeteners, and surfactants.

Examples of the disintegrating agent include celluloses such as croscarmellose sodium, carmellose, carmellose calcium, carmellose sodium, and low substituted hydroxypropyl cellulose; starches such as carboxy methyl starch sodium, hydroxypropyl starch, rice starch, wheat starch, corn starch, potato starch, and partly pregelatinized starch; and crospovidone.

Examples of the binder include saccharides such as white sugar, glucose, lactose, and fructose; sugar alcohols such as mannitol, xylitol, maltitol, erythritol, and sorbitol; gelatin; water-soluble polysaccharides such as pullulan, carrageenan, locust bean gum, agar, glucomannan, xanthan gum, tamarind gum, pectin, alginic acid sodium, and gum arabic; celluloses such as microcrystalline cellulose, powder cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and methyl cellulose; starches such as pregelatinized starch and starch glue; synthetic polymers such as polyvinylpyrrolidone, carboxyvinyl polymer, and polyvinyl alcohol; and inorganic substances such as calcium hydrogenphosphate, calcium carbonate, synthetic hydrotalcite, and magnesium silicate aluminate.

Examples of the fluidizing agent include hydrous silicon dioxide and light anhydrous silicic acid. Examples of the lubricant include magnesium stearate, calcium stearate, stearic acid, sucrose fatty acid esters, and talc. Examples of the flavoring substances include glutamic acid, fumaric acid, succinic acid, citric acid, sodium citrate, tartaric acid, malic acid, ascorbic acid, sodium chloride, and 1-menthol.

Examples of the fragrances include oils such as orange, vanilla, strawberry, yogurt, menthol, fennel, cinnamon, picea, and peppermint oils; and green tea powder. Examples of the colorants include food dyes such as food dye red No. 3, food dye yellow No. 5, and food dye blue No. 1; sodium copper chlorophyllin, titanium oxide, and riboflavin. Examples of the sweeteners include aspartame, saccharin, dipotassium glycyrrhizinate, stevia, maltose, maltitol, mizuame, and powder of Hydrangea macrophylla var. thunbergii. Examples of the surfactants include phosphorus lipid, glycerol fatty acid esters, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, and polyoxyethylene hardened castor oil.

In the present invention, the active ingredient indicates active pharmaceutical ingredients, pesticide ingredients, fertilizer ingredients, livestock food ingredients, food ingredients, cosmetic ingredients, dyes, fragrances, metals, ceramics, catalysts, surfactants, and the like, and may be in any form of powder, crystal, oil, and solution, for example. The active ingredient may be coated to control dissolution, reduce bitterness, and the like. The cellulose powder according to the present invention is particularly effective to the active ingredients having bad odors.

Examples of active pharmaceutical ingredients include Kampo medicines, crude drugs, and natural and synthetic pharmaceuticals orally administrated and having bad odors, such as antipyretic analgesic antiphlogistics, hypnotics, antisleepiness drugs, antidizziness drugs, pediatric analgesics, stomachics, antacid, digestive drugs, cardiotonics, antiarrhythmic drugs, antihypertensives, vasodilators, diuretics, antiulcer drugs, intestinal regulators, antiosteoporosis drugs, antitussive expectorants, antiasthmatic drugs, antibacterial drugs, anti-pollakiuria drugs, analeptics, and vitamins.

For example, examples of Kampo medicines are as follows.

These ingredients may be processed powders of raw powders or extract powders prepared by extracting raw powders, condensing the extracts, and drying the extract.

Examples of crude drugs include fennel, corydalis tuber, scutellaria root, coptis rhizome, zedoary, glycyrrhiza, platycodon root, curcuma aromatica, schizonepeta spike, cinnamon bark, cyperus rhizome, magnolia bark, gardenia fruit, cornus fruit, dioscorea rhizome, rehmannia root, lithospermum, peony root, amomum seed, ginger, processed ginger, cnidium rhizome, atractylodes lancea rhizome, perilla herb, rhubarb, jujube, alisma tuber, clove, citrus unshiu peel, Japanese angelica root, eucommia bark, ginseng, mint, pinellia tuber, atractylodes rhizome, poria sclerotium, processed aconite root, saposhnikovia root and rhizome, moutan bark, oyster shell, ephedra herb, Alpinia officinarum Hance, forsythia fruit, and deer antler velvet. Examples of the ingredients contained in Bofutsushosan include ephedra herb (Ephedra sinica Stapf, Ephedra intermedia Schrenk et C.A. Meyer, Ephedra equisetina Bunge), glycyrrhiza (Glycyrrhiza uralensis Fischer, Glycyrrhiza glabra Linne), ginger (Zingiber officinale Roscoe), Schizonepeta spike (Schizonepeta tenuifolia Briquet), Forsythia fruit (Forsythia suspense Vahl, Forsythia viridissima Lindley), Japanese angelica root (Angelica acutiloba Kitagawa, Angelica acutiloba Kitagawa var. sugiyamae Hikino), peony root (Paeonia lactiflora Pallas), cnidium rhizome (Cnidium officinale Makino), gardenia fruit (Gardenia jasminoides Ellis), mint (Mentha arvensis Linne var. piperascens Malinvaud), saposhnikovia root and rhizome (Saposhnikovia divaricata Schischkin), rhubarb (Rheum palmatum Linne, Rheum tanguticum Maximowicz, Rheum officinable Baillon, Rheum coreanum Nakai, or interspecific hybrids thereof), atractylodes rhizome (Atractylodes japonica Koidzumi ex Kitamura, Atractylodes ovata De Candolle), platycodon root (Platy grandiflorum A. De Candolle), and scutellaria root (Scutellariae baicalensis Georgi). These ingredients may be processed powders of raw powders or extract powders prepared by extracting raw powders, condensing the extracts, and drying the extract.

The content of the active ingredient in the molded article according to the present invention is preferably 0.01 to 99% by weight based on the weight of the molded article. At a content of the active ingredient of 0.01% by weight or more, sufficient efficacy can be expected. At a content of 99% by weight or less, abrasive wear or breakage of the molded article can be prevented by a sufficient amount of an excipient to give satisfactory physical properties to the molded articles.

In the present invention, the tablet indicates a molded article including the cellulose powder according to the present invention and optional other additives, which can be prepared by one of a direct compression tableting method, a granule compression method, and wet granulation compression (extragranular addition of cellulose powder). Among these, tablets prepared by the direct compression tableting method are particularly preferred.

Among the molded articles according to the present invention, preferably the tablets, when the tablet contains one or more active ingredients and one or more additives selected from saccharides, sugar alcohols, starches, and disintegrating agents, compounding of the cellulose powder according to the present invention attains a molded article, preferably a tablet having a hardness of 50 to 200 N, a tensile strength of 0.1 to 12 MPa, a friability of 0 to 0.5%, a swelling rate of the diameter of the molded article, preferably the tablet in acetone of 0 to 3.3%. The amount of the cellulose powder compounded with the molded article, preferably the tablet is preferably 5 to 90% by weight. An amount of compounding in the range of 5 to 90% by weight is preferred because physical properties described above are well-balanced.

The compounding of the cellulose powder according to the present application with a molded article, preferably a tablet can attain a tablet having a hardness, a tensile strength, and a friability in the ranges above, a swelling rate of the diameter of the molded article, preferably the tablet in acetone of 0 to 3.3%. The swelling rate of the diameter of the molded article, preferably the tablet in acetone is preferably 0 to 3%, more preferably 0 to 2%. A swelling rate of the diameter of the molded article, preferably the tablet in acetone in the range of 0 to 3.3% is preferred because the hardness, the tensile strength, and the friability are well-balanced.

The swelling rate of the diameter of the molded article, preferably the tablet in acetone is defined by a rate of change in the diameter (mm) of the molded article (preferably tablet) before and after the molded article (the tablet) is dipped in acetone (25° C.) for 60 seconds, and is calculated by the following expression:

swelling rate (%) of diameter of molded article (tablet)=[(diameter of molded article (tablet) after dipping in acetone)−(diameter of molded article (tablet) before dipping in acetone)/(diameter of molded article (tablet) before dipping in acetone)]×100

High compactibility of the cellulose powder according to the present invention results in a low swelling rate of the diameter of the molded article, preferably the tablet in acetone. A number of drugs have poor compactibility. If such a drug is contained in a molded article, preferably a tablet in a higher content, the physical properties of the drug are reflected. The resulting molded article (tablet) has low hardness and is readily worn. At this time, with a cellulose powder having insufficient compactibility, a molded article, preferably a tablet having a hardness of 50 N or more and a friability of 0.5% or less may not be attained. In contrast, use of the cellulose powder according to the present invention can give a hardness and friability suitable for practical use to the molded article, preferably the tablets. A preferred range of a drug contained in the molded article, preferably the tablet is 30 to 90% by mass, preferably 50 to 80% by mass. The content in the range of 30 to 90% by mass are preferred from the viewpoint of hardness and friability.

If the swelling rate of the diameter of the molded article, preferably the tablet in acetone is 0 to 3.3%, the resulting molded article, preferably the tablet can disintegrate and dissolve quickly. The amount of total organic carbon derived from the residual impurities in the molded article residues or in the cellulose powder obtained through washing of the molded article, preferably the tablet with acetone, ethanol, pure water, and ethanol sequentially and extraction is preferably more than 0.07 and 0.3% or less. The amount in the range of more than 0.07 and 0.3% or less is preferred from the viewpoint of compactibility. An amount of total organic carbon derived from residual impurities of 0.09 to 0.15% is preferred from the viewpoints of bad odors suppression, whiteness, and gloss.

The amount of total organic carbon derived from the residual impurities in the molded article, preferably the tablet residues is defined by the difference (%) between the amount of total organic carbon (TOC) in the molded article residues extracted from the molded article residues with pure water (80 mL) and the amount of TOC in the molded article residues extracted from the molded article residues with an aqueous solution of 1% sodium hydroxide (80 mL). When the molded article residues are cellulose powder, the molded article residues are sufficiently washed with pure water. For this reason, the amount of total organic carbon (%) during extraction with pure water in the molded article residues is close to zero, and the amount of total organic carbon derived from the residual impurities in the molded article residues is substantially equal to the amount of total organic carbon (%) during extraction with 1% NaOH. When the amount of total organic carbon (%) during extraction with pure water is detected, removal of impurities by washing with pure water may be insufficient or removal of acetone and ethanol residuals by drying may be insufficient. For this reason, the amount of pure water used in extraction is increased 1.3 to 2 times, or the drying temperature is adjusted to 100 to 120° C. and the drying time is adjusted to 3 to 5 hr. The amount of total organic carbon derived from the residual impurities in the molded article residues obtained through washing of the molded article with acetone, ethanol, pure water, and ethanol sequentially and extraction can be checked by the following procedure.

(i) 120 g of a molded article is placed in a 500 ml beaker, and 300 g of acetone is added. The mixture is stirred with a stirrer until molded article fragments disappear. The solution is vacuum filtered (with a Buchner funnel, and a filter paper for quantitative analysis, 5 C, diameter: 110 mm). When molded article fragments are found, the solution is subjected to ultrasonic treatment for 10 minutes, and is stirred for 30 minutes. This operation is repeated until the molded article fragments disappear.

-   (ii) 100 mL of ethanol is added to the residues on the filter paper,     is mixed with the residues with a spatula sufficiently, and is     vacuum filtered (this operation is repeated 3 times). The     ingredients barely soluble in water are removed by the     operations (i) and (ii). -   (iii) The residues treated in (ii) are added to 1000 mL of pure     water, is stirred with a stirrer for 10 minutes, and is vacuum     filtered. -   (iv) The residues treated in (iii) are added to 600 ml of pure     water, is stirred with a stirrer for 10 minutes, and is vacuum     filtered. -   (v) The residues treated in (iv) are added to 1000 mL of pure water,     and the mixture is heated at 80 to 100° C. for 30 minutes while the     mixture is stirred with a stirrer. After cooling to 20 to 30° C., 5     μg/L of α-amylase is added, is stirred at 37° C. for 30 minutes, and     is vacuum filtered.

(vi) 150 mL of ethanol is added to the residues treated in (v). The residues are mixed with a spatula sufficiently, and is vacuum filtered (this operation is repeated 3 times). The water-soluble ingredients and starches are removed by the operations (iii) to (vi). The water-soluble ingredients include saccharides and sugar alcohols, and can be determined by a known method.

-   (vii) The residues on the filter paper are scraped off therefrom,     and are placed in a petri dish. The residues are dried at room     temperature (20 to 30° C.) until a smell of ethanol disappears, and     are dried at 100° C. for 3 hours to prepare a sample for     measurement. -   (viii) About 2 g of the dried residues are placed in a cell for     measurement, and are measured by near-infrared spectroscopy. Thus,     an absorption spectrum is obtained (name of the apparatus:     InfraAlyzer 500, manufacturer: BRAN+LUBBE). When the peaks     indicating second derivative values are detected at 1692 nm in an     NIR absorption spectrum, the cellulose powder content (C (%)) in the     molded article residues is calculated by the following expression:

C (%)=intensity of NIR second derivative spectrum×316583+95.588

When the peaks indicating the second derivative values in the NIR absorption spectrum are found at 1692 nm, crospovidone residues are contained in addition to the cellulose powder. The content of the cellulose powder in the dried residues is determined by the above expression. Instead of the molded article in (i), three composition powders of cellulose powder/crospovidone=100/0, 50/50, and 0/100 are prepared. Through the operations (i) to (vii), dried residues are each prepared. The intensities of the NIR second derivative spectrums are measured with the InfraAlyzer 500 (manufacturer: BRAN+LUBBE). From the three calibration curves, the coefficients in the above expression can be determined.

When no peaks of second derivative values in the NIR absorption spectrum are detected at 1692 nm, and the amount of total organic carbon (TOC) extracted with pure water (80 mL) from the dried residues in the dried residues is 0.0%, the dried residues are composed of only the cellulose powder. At an amount of TOC of more than 0.0%, disintegrating agents other than starch and crospovidone may be contained. To remove these, dried residues are dispersed in 50 mL of pure water, and are passed through a sieve having an opening of 10 μm to remove particles other than the cellulose powder. The filtrate is evaporated, and the resulting product is dried and solidified to prepare dried residues in (ix). When the amount of total organic carbon (%) in the residues during extraction with pure water exceeds 0.0% even after this operation, the dried residues are dispersed in 50 mL of pure water (may be optionally subjected to ultrasonic and homogenizing treatments), and are centrifuged at 2000 G. The supernatant is evaporated, and the resulting product is dried and solidified to prepare dried residues in (ix).

(ix) <Case Where Peaks of Second Derivative Values in MR Absorption Spectrum are Detected at 1692 nm in (viii)>

The dried residues (A (g), 4 to 4.5 g as a guideline) are weighed, and are added to 80 ml of 1% NaOH. The mixture is stirred with a stirrer for 5 minutes, and is vacuum filtered. The filtrate is extracted to measure the volume (X (mL)). The filtrate is acidified with hydrochloric acid (pH: 2 to 3). The amount of total organic carbon (TOC_(1%NaOH) (mg/L)) is measured with a total organic carbon analyzer (manufactured by SHIMADZU Corporation, TOC-VCSH, by a TC-IC method). Because the residues are sufficiently washed with pure water, the amount of total organic carbon (%) during extraction with pure water is considered as zero. Accordingly, the amount of organic carbon derived from the residual impurities in the cellulose powder contained in the residue is equal to the amount of total organic carbon (%) during extraction with 1% NaOH. Calculation is performed as follows:

amount of cellulose powder residue (B(g)) in residue extracted from molded article=A×C/100

amount of total organic carbon (Y(mg)) in cellulose powder residue=(TOC _(1%NaOH)/1000)×X−0.4/100×(A−B)×1000

The coefficient 0.4 is the amount of total organic carbon (%) when 2.5 g of a crospovidone powder is used as the molded article in (i) to prepare dried residues through the treatments to (vii), and the dried residues are extracted with 80 ml of 1% NaOH.

amount of total organic carbon (%) derived from residual impurities in molded article residues obtained through washing of the molded article with acetone, ethanol, pure water, and ethanol sequentially and extraction=Y/(1000×B)×100=Y/(10×B)

<Case Where Peaks of Second Derivative Values in NIR Absorption Spectrum are not Detected at 1692 nm in viii)>

The dried residues (A_(H2O) (g): during extraction with pure water, A_(1%NaOH) (g): during extraction with a 1% NaOH aqueous solution) are weighed, and 80 mL of pure water or 1% NaOH aqueous solution is added. The mixture is stirred in a beaker for 5 minutes (with a stirrer), and is vacuum filtered (with a filter paper for quantitative analysis, 5 C, diameter: 110 mm) to remove the dried residues and obtain a filtrate. After the volume of the total amount of the filtrate (V_(H2O): total amount (mL) in use of pure water, V_(1%NaoH): total amount (mL) in use of 1% NaOH) is measured, the filtrate is acidified with hydrochloric acid (pH: 2 to 3), and the amount of total organic carbon (TOC (mg/L)) was measured with a total organic carbon analyzer (manufactured by SHIMADZU Corporation, TOC-VCSH, by a TC-IC method). The TOC in use of pure water is TOC_(H2O), and the TOC in use of 1% NaOH is TOC_(1%NaOH). The amount of organic carbon derived from the residual impurities in the molded article residues is calculated by the following expressions:

amount of total organic carbon (%) derived from residual impurities in molded article residues=amount of total organic carbon (%) during extraction with 1% NaOH−amount of total organic carbon (%) during extraction with pure water

amount of total organic carbon (%) during extraction with 1% NaOH:=[(TOC _(1%NaOH)(mg/L)/1000)×V _(1%NaOH) (mL)]/A _(1%NaOH)×1000 (mg)×100

amount of total organic carbon (%) during extraction with pure water:=[(TOC _(H2O)(mg/L)/1000)×V _(H2O)(mL)]/A _(H2O)×1000 (mg)×100

The cellulose powder according to the present invention can be used in wet granulation as a sugar-coating reinforcing agent in sugar-coated tablets, an extruding property improver in extrusion granulation, and granulation aids in crush granulation, fluidized bed granulation, high speed high shear granulation, tumbling granulation, and the like to prepare granule agents and granules for pressing. The granules for pressing can be prepared by dry granulation. Furthermore, tablets can be prepared by a method (wet granulation compression (extragranular addition of cellulose powder)) in which the cellulose powder according to the present invention is added to the granules for pressing prepared by such a known method, and the mixture is compressed. The cellulose powder according to the present invention can delay the granulation rate when active pharmaceutical ingredients having high moisture absorbing properties and high water solubility are granulated, so that generation of coarse particles are reduced to increase granulation yield. The cellulose powder according to the present invention, which has a low particle density, provides bulky granulated products. For this reason, the cellulose powder contributes to preparation of granules for pressing having high compression compactibility. The cellulose powder according to the present invention can be compounded with powder medicines to, for example, prevent blocking and improve fluidity, or can be compounded with encapsulated formulations to, for example, improve filling properties.

EXAMPLES

The present invention will now be described in more detail by way of Examples, but the scope of the present invention will not be limited to these. Physical properties in Examples and Comparative Examples were measured by the following methods.

1) Average Degree of Polymerization (−)

The average degree of polymerization is a value determined by a copper ethylene diamine solution viscosity method described in a microcrystalline cellulose check test (3) in the 15th edition of the Pharmacopeia of Japan.

2) Loss on Drying (%)

1 g of a powder was dried at 105° C. for 3 hours, and the amount of weight reduction was expressed by weight percentage.

3) Volume Average Particle Size (μm) of Cellulose Particle in Cellulose Dispersion Liquid

The particle size of particles in the cellulose dispersion liquid after hydrolysis or before drying was determined by the following procedure. A cellulose dispersion liquid was dropped onto a microscope stand. A glass slide was placed over the droplets. The droplets were dried, and an optical microscopic image was taken with a microscope. The optical microscopic image was subjected to image analysis processing (manufactured by Inter Quest Co., Ltd., apparatus: Hyper 700, software: Imagehyper). Among rectangles circumscribing a particle, the long side of the rectangle having the smallest area was determined, and the cumulative number 50% particle size was defined as the volume average particle size. At least 100 or more particles were subjected to image analysis processing.

4) Weight Average Particle Size (μm) of Cellulose Powder

The weight average particle size of a powder sample was determined by sieving 10 g of the sample with a low tapping sieve shaker (sieve shaker type A manufactured by Heiko Seisakusho, Ltd.) and a JIS standard sieve (Z8801-1987) for 10 minutes to determine the particle size distribution. The particle size distribution was expressed as a cumulative weight 50% particle size.

5) Apparent Specific Volume (cm³/g)

A powder sample was roughly placed in a 100 cm³ glass measuring cylinder with a constant volume feeder or the like over 2 to 3 minutes. The top surface of the powder layer was leveled with a soft brush like an ink brush. The volume thereof was read, and was divided by the weight of the powder sample to determine the apparent specific volume. The weight of the powder was properly determined to have a volume of about 70 to 100 cm³.

6) Apparent Tapping Density (g/cm³)

With a commercially available powder physical property analyzer (manufactured by Hosokawa Micron Corporation, powder tester type PT-R), a powder was placed in a 100 cm³ cup, and was tapped 180 times. The volume of the cup was divided by the weight of the powder layer remaining in the cup to determine the apparent tapping density.

7) Intraparticle Pore Volume (cm³/g)

Pore distribution was determined with AutoPore, type 9520 (trade name) manufactured by SHIMADZU Corporation by mercury porosimetry. The sample powders used in the measurement were dried at room temperature for 15 hours under reduced pressure. From the pore distribution determined in the measurement at an initial pressure of 20 kPa, the total volume of pores having a diameter of 0.1 to 15 μm was defined as the intraparticle pore volume.

8) Amount of Organic Carbon (%) Derived From Residual Impurities

80 mL of pure water or a 1% NaOH aqueous solution was added to a cellulose powder (W (mg), 5000 mg as a guideline), and was stirred for 5 minutes in a beaker (with a stirrer). Then, the cellulose powder was removed through vacuum filtration (with a filter paper for quantitative analysis, 5 C, diameter: 110 mm) to obtain a filtrate. The total volume of the filtrate was measured (where the total volume in use of water was V_(H2O), and the total volume in use of 1% NaOH was V_(1%NaOH) (mL)), and the filtrate was acidified with hydrochloric acid (pH: 2 to 3). Then, the amount of total organic carbon (TOC (mg/L)) was measured with a total organic carbon analyzer (manufactured by SHIMADZU Corporation, TOC-VCSH, by a TC-IC method). The TOC in use of pure water was TOC_(H2O), and the TOC in use of 1% NaOH was TOC_(1%NaOH). The amount of organic carbon derived from the residual impurities was calculated by the following expressions:

amount of organic carbon (%) derived from residual impurities=amount of total organic carbon (%) during extraction with 1% NaOH−amount of total organic carbon (%) during extraction with pure water

amount of total organic carbon (%) during extraction with 1% NaOH:=[(TOC _(1%NaOH)(mg/L)/1000)×V _(1%NaOH)(mL)]/W(mg)×100

amount of total organic carbon (%) during extraction with pure water:=[(TOC _(H2O)(mg/L)/1000)×V _(H2O)(mL)]/W(mg)×100

9) Water Absorption Capacity (cm³/g)

Pure water was dropped to 2 g of a cellulose powder (in terms of dried powder), and when necessary the cellulose powder was kneaded with a spatula or the like so as to be mixed with the dropped water. A point when water bled out on the surface of the mixture was defined as an end point, and the amount of pure water dropped (V) was determined. The water absorption capacity was calculated by the following expression. The average value of three values obtained in the measurement was used.

Water absorption capacity (cm³/g)=V/2

10) Angle of Repose (°)

Using a Sugihara type repose angle measuring apparatus (slit size: depth: 10 mm, width: 5n height: 140 mm, a protractor was disposed at a position of a width of 50 mm), the dynamic self-fluidity was measured when the cellulose powder was dropped into the slit with a constant volume feeder at a rate of 3 g/min. The angle formed by the bottom surface of the apparatus and the formed layer of the cellulose powder is an angle of repose.

11) Hardness (N)

Cylindrical molded articles or tablets were broken with a Schleuniger durometer (manufactured by Freund Corporation, type 6D) by applying a load in the diameter direction of the cylindrical molded article or the tablet, and the load at this time was measured. The hardness was expressed as the number average of five samples. A cylindrical molded article composed of 100% cellulose powder was prepared as follows. 0.5 g of a sample was placed in a die (manufactured by Kikusui Seisakusho Ltd., material SUK2, 3 was used), and was compressed at 10 MPa with a flat-surface punch (manufactured by Kikusui Seisakusho Ltd., material SUK2, 3 was used) having a diameter of 1.13 cm (bottom area: 1 cm²). The stress was kept for 10 seconds to prepare a cylindrical molded article (a compressor manufactured by AIKOH ENGINEERING CO., LTD., PCM-1A was used, the compression rate was about 10 cm/min). The hardness suitable for practical use is 50 N or more in the tablet having a diameter of 8 mm and is 70 N or more in the tablet having a diameter of 9 mm or more.

12) Tensile Strength (MPa)

The hardness of a tablet: H (N), the diameter of the tablet (the largest diameter was used in caplets or the like): D (mm), and the thickness of the tablet: T (mm) were determined, and the tensile strength was calculated by the following expression:

tensile strength (MPa)=2×H/(3.14×D×T)

13) Friability of Tablet (%)

The weights (Wa) of 20 tablets were measured. These tablets were placed in a tablet friability tester (PTFR-A, manufactured by Pharma Test Apparatebau AG), and were rotated at 25 rpm for 4 minutes. Then, fine powders adhering to the tablets were removed, and the weights (Wb) were again measured. The friability was calculated by the expression (7):

friability=100×(Wa−Wb)/Wa

Tablets suitable for practical use should have a friability of 0.5% or less.

14) Sensory Evaluation on Tablet

Bofutsushosan extract alone or 20 tablets containing Bofutsushosan were placed in a 100 mL glass air-tight bottle. After 30 minutes had passed, the bottle was opened to evaluate the odor. Ten evaluators who were sensitive to odors evaluated the odor on a five-level rating system where the odor from the dry extract of Bofutsushosan alone was rated as 3. A larger value indicated that the bad odor was reduced and an aroma was likely to be increased. If the odor from the dry extract of Bofutsushosan alone was only masked to make the odor weaker, the sample was rated as “0.”

15) Whiteness of Tablet (%)

The values L, a, and b were determined with a spectrocolorimeter (SE-2000, manufactured by Nippon Denshoku Industries Co., Ltd.) to calculate the whiteness by the following expression:

whiteness=100−[(100−L)²+(a ² +b ²)]^(0.5)

L: brightness, a: saturation (green to red), b: saturation (blue to yellow)

16) Gloss of Tablet

The gloss was visually evaluated on the following 4-level ranking system:

⊙: gloss over the tablet

◯: gloss on most of the tablet

Δ: gloss on part of the tablet

X: no gloss

Example 1

2 kg of a commercially available SP pulp (degree of polymerization: 1030, level-off degree of polymerization: 220) was shredded, and was added to 30 L of an aqueous solution of 0.05% hydrochloric acid. While the mixture was stirred (at a stirring rate of 234 rpm) with a low speed stirrer (manufactured by Ikebukuro Horo Kogyo Co., Ltd., 30 LGL reactor, blade diameter: about 30 cm), the pulp was hydrolyzed at 145° C. for 70 minutes. The resulting acid-insoluble residues were filtered with a suction funnel. The filtered residues were washed with 70 L of pure water 4 times, and were neutralized with aqueous ammonia. The residues were placed in a 90 L plastic bucket, and pure water was added. While the mixture was stirred (at a stirring rate of 500 rpm) with a three-one motor (manufactured by HEIDON, type BLh1200, 8 M/M, blade diameter: about 10 cm), a cellulose dispersion liquid having a concentration of 16% was prepared (pH: 7.8, IC: 55 μS/cm).

The cellulose dispersion liquid was spray dried (liquid feed rate: 6 L/hr, inlet temperature: 180 to 220° C., outlet temperature: 50 to 70° C.) to prepare Cellulose powder A (loss on drying: 4.0%). The physical properties of Cellulose powder A and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder A are shown in Table 1.

Example 2

2 kg of a commercially available SP pulp (degree of polymerization: 1030, level-off degree of polymerization: 200) was shredded, and was added to 30 L of an aqueous solution of 0.08% hydrochloric acid. While the mixture was stirred (at a stirring rate of 234 rpm) with a low speed stirrer (manufactured by Ikebukuro Horo Kogyo Co., Ltd., 30 LGL reactor, blade diameter: about 30 cm), the pulp was hydrolyzed at 140° C. for 110 minutes. The resulting acid-insoluble residues were filtered with a suction funnel. The filtered residues were washed with 70 L of pure water 4 times, and were neutralized with aqueous ammonia. The residues were placed in a 90 L plastic bucket, and pure water was added. While the mixture was stirred (at a stirring rate of 500 rpm) with a three-one motor (manufactured by HEIDON, type BLh1200, 8 M/M, blade diameter: about 10 cm), a cellulose dispersion liquid having a concentration of 18% was prepared (pH: 7.5, IC: 60 μS/cm).

The cellulose dispersion liquid was spray dried (liquid feed rate: 6 L/hr, inlet temperature: 180 to 220° C., outlet temperature: 50 to 70° C.) to prepare Cellulose powder B (loss on drying: 3.5%). The physical properties of Cellulose powder B and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder B are shown in Table 1.

Example 3

2 kg of a commercially available KP pulp (degree of polymerization: 1030, level-off degree of polymerization: 190) was shredded, and was added to 30 L of an aqueous solution of 0.10% hydrochloric acid. While the mixture was stirred (at a stirring rate of 234 rpm) with a low speed stirrer (manufactured by Ikebukuro Horo Kogyo Co., Ltd., 30 LGL reactor, blade diameter: about 30 cm), the pulp was hydrolyzed at 135° C. for 100 minutes. The resulting acid-insoluble residues were filtered with a suction funnel. The filtered residues were washed with 70 L of pure water 4 times, and were neutralized with aqueous ammonia. The residues were placed in a 90 L plastic bucket, and pure water was added. While the mixture was stirred (at a stirring rate of 500 rpm) with a three-one motor (manufactured by HEIDON, type BLh1200, 8 M/M, blade diameter: about 10 cm), a cellulose dispersion liquid having a concentration of 19% was prepared (pH: 7.5, IC: 50 μS/cm).

The cellulose dispersion liquid was spray dried (liquid feed rate: 6 L/hr, inlet temperature: 180 to 220° C., outlet temperature: 50 to 70° C.) to prepare Cellulose powder C (loss on drying: 3.3%). The physical properties of Cellulose powder C and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder C are shown in Table 1.

Example 4

2 kg of a commercially available KP pulp (degree of polymerization: 1030, level-off degree of polymerization: 130) was shredded, and was added to 30 L of an aqueous solution of 0.15% hydrochloric acid. While the mixture was stirred (at a stirring rate of 80 rpm) with a low speed stirrer (manufactured by Ikebukuro Horo Kogyo Co., Ltd., 30 LGL reactor, blade diameter: about 30 cm), the pulp was hydrolyzed at 110° C. for 105 minutes. The resulting acid-insoluble residues were filtered with a suction funnel. The filtered residues were washed with 70 L of pure water 4 times, and were neutralized with aqueous ammonia. The residues were placed in a 90 L plastic bucket, and pure water was added. While the mixture was stirred (at a stirring rate of 500 rpm) with a three-one motor (manufactured by HEIDON, type BLh1200, 8 M/M, blade diameter: about 10 cm), a cellulose dispersion liquid having a concentration of 19% was prepared (pH: 7.5, IC: 65 μS/cm).

The cellulose dispersion liquid was spray dried (liquid feed rate: 6 L/hr, inlet temperature: 180 to 220° C., outlet temperature: 50 to 70° C.) to prepare Cellulose powder D (loss on drying: 3.2%). The physical properties of Cellulose powder D and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder D are shown in Table 1.

The cellulose powders according to the present application (Examples 1 to 4) have about 20 to 30% higher compactibility than that of the conventional cellulose powders (Comparative Examples 1 and 2) even when the apparent specific volume is the same, as shown in FIG. 1.

Example 5

Cellulose powder E was prepared by the same operation as in Example 3 except that the concentration of hydrochloric acid was 0.16%.

The physical properties of Cellulose powder E and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder E are shown in Table 1.

Example 6

Cellulose powder F was prepared by the same operation as in Example 3 except that hydrolysis time was 120 minutes.

The physical properties of Cellulose powder F and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder F are shown in Table 1.

Example 7

Cellulose powder G was prepared by the same operation as in Example 3 except that the hydrolysis time was 60 minutes.

The physical properties of Cellulose powder G and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder G are shown in Table 1.

Example 8

Cellulose powder H was prepared by the same operation as in Example 3 except that the hydrolysis temperature was 90° C.

The physical properties of Cellulose powder H and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder H are shown in Table 1.

Example 9

Cellulose powder I was prepared by the same operation as in Example 1 except that the hydrolysis time was 45 minutes.

The physical properties of Cellulose powder I and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder I are shown in Table 1.

Example 10

Cellulose powder J was prepared by the same operation as in Example 2 except that the concentration of hydrochloric acid was 0.28%, the hydrolysis temperature was 110° C., and the hydrolysis time was 60 minutes.

The physical properties of Cellulose powder J and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder J are shown in Table 1.

Example 11

Cellulose powder K was prepared by the same operation as in Example 3 except that the concentration of hydrochloric acid was 0.08%, the hydrolysis temperature was 135° C., and the hydrolysis time was 80 minutes.

The physical properties of Cellulose powder K and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder K are shown in Table 1.

Comparative Example 1

2 kg of a commercially available SP pulp (degree of polymerization: 1030, level-off degree of polymerization: 220) was shredded, and was hydrolyzed with 30 L of an aqueous solution of 0.14 N (0.49%) hydrochloric acid at 121° C. for 1 hour. The resulting acid-insoluble residues were filtered with a suction funnel. The filtered residues were washed with 70 L of pure water 4 times, and were neutralized with aqueous ammonia. The residues were placed in a 90 L plastic bucket. While the mixture was stirred with a three-one motor, a cellulose dispersion liquid having a concentration of 17% was prepared (pH: 6.4, IC: 64 μS/cm).

The cellulose dispersion liquid was spray dried (liquid feed rate: 6 L/hr, inlet temperature: 180 to 220° C., outlet temperature: 70° C.), and coarse particles were removed with a 325 mesh sieve to prepare Cellulose powder L (loss on drying: 4.1%, corresponding to Example 1 in JP 40-26274 B). The physical properties of Cellulose powder L and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder L are shown in Table 1.

Comparative Example 2

A commercially available KP pulp (degree of polymerization: 840, level-off degree of polymerization: 145) was hydrolyzed in an aqueous solution of 0.7% hydrochloric acid at 125° C. for 150 minutes. The hydrolyzed residues were neutralized, were washed, and were filtered to prepare a wet cake. The wet cake was sufficiently ground with a kneader. Ethanol was added in a volume ratio of ethanol to the wet cake of 1:1. The solution was compression filtered, and was dried with air. The dried powder was milled with a hammer mill, and coarse particles were removed with a 40 mesh sieve to prepare Cellulose powder M (dry weight: 3.0%, corresponding to Example 1 in JP 56-2047 A). The physical properties of Cellulose powder M and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder M are shown in Table 1.

Comparative Example 3

Cellulose powder N was prepared by the same operation as in Example 3 except that the hydrolysis temperature was 160° C. The physical properties of Cellulose powder N and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder N are shown in Table 1.

Comparative Example 4

Cellulose powder O was prepared by the same operation as in Example 3 except that the hydrolysis temperature was 90° C., and the hydrolysis time was 50 minutes. The physical properties of Cellulose powder 0 and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder 0 are shown in Table 1.

Comparative Example 5

Cellulose powder P was prepared by the same operation as in Example 1 except that the hydrolysis temperature was 25° C., and the hydrolysis time was 30 minutes. The physical properties of Cellulose powder P and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder P are shown in Table 1.

Comparative Example 6

Cellulose powder Q was prepared by the same operation as in Example 2 except that the concentration of hydrochloric acid was 0.50%, the hydrolysis temperature was 90° C., and the hydrolysis time was 35 minutes. The physical properties of Cellulose powder Q and the physical properties of a cylindrical molded article prepared by compressing 100% Cellulose powder Q are shown in Table 1.

TABLE 1 Physical properties of cellulose dispersion liquid Physical properties Reaction conditions Volume Volume of cellulose powder Concen- average average Average Weight tration of Hydrolysis particle particle degree of average hydro- tempera- Hydrolysis size (μm) size (μm) polymeri- particle Cellulose chloric ture time after before zation size powder acid (%) (° C.) (min) reaction drying (−) (μm) Example 1 A 0.05 145 70 146 49 280 40 2 B 0.08 140 110 120 47 200 60 3 C 0.10 135 100 115 45 190 50 4 D 0.15 110 105 70 40 130 240 5 E 0.16 135 100 65 38 120 56 6 F 0.10 135 120 80 43 180 44 7 G 0.10 135 60 151 55 180 59 8 H 0.10 90 100 180 65 330 70 9 I 0.05 145 45 156 54 330 40 10 J 0.28 110 60 120 47 185 45 11 K 0.08 135 80 123 44 200 80 Comparative 1 L 0.49 121 60 65 30 220 49 Example 2 M 0.70 125 150 50 25 145 40 3 N 0.10 160 100 63 28 170 45 4 O 0.10 90 50 210 75 400 35 5 P 0.05 25 30 294 110 580 210 6 Q 0.50 90 35 170 75 360 90 Physical properties of cellulose powder Cylindrical Amount of molded organic article carbon (%) composed of Apparent derived Intraparticle Water 100% cellulose specific Tapping Angle of from pore absorption powder volume density repose residual volume capacity Hardness (cm³/g) (g/cm³) (°) impurites (cm³/g) (cm³/g) (N) Example 1 3.9 0.32 43 0.145 0.25 3.0 75 2 3.3 0.45 38 0.131 0.21 2.5 70 3 3.1 0.51 42 0.116 0.20 2.3 65 4 2.6 0.59 36 0.090 0.12 1.8 55 5 2.5 0.58 38 0.085 0.21 1.9 48 6 2.5 0.61 37 0.080 0.19 1.8 47 7 4.2 0.29 48 0.152 0.20 3.5 88 8 5.0 0.22 54 0.164 0.22 4.0 90 9 10.0 0.21 56 0.291 0.15 3.9 100 10 3.4 0.55 45 0.160 0.19 2.4 70 11 4.5 0.35 38 0.248 0.21 2.5 85 Comparative 1 3.1 0.41 44 0.070 0.24 2.2 41 Example 2 2.0 0.63 35 0.062 0.18 1.9 35 3 1.9 0.61 48 0.063 0.18 1.8 32 4 15.1 0.12 63 0.330 0.22 4.5 38 5 18.0 0.08 65 0.420 0.18 5.5 31 6 14.1 0.19 59 0.341 0.19 4.3 42

Example 12

250 g of Bofutsushosan Extract-F (manufactured by Alps Pharmaceutical Industry Co., Ltd.), 500 g of Cellulose powder A, 220 g of spray dried lactose (SuperTab, manufactured by DMV-Fonterra Excipients GmbH & Co. KG), 30 g of pregelatinized starch “Swelstar” PD-1 (manufactured by Asahi Kasei Chemicals Corporation) were mixed in a plastic bag for 3 minutes. 10 g of vegetable magnesium stearate (TA HEI CHEMICAL INDUSTRIAL CO., LTD.) was added to the mixture, and the obtained mixture was further mixed in the plastic bag for 30 seconds. The mixture was pressed with a rotary presser (“Clean Press Correct 12HUK” (trade name), manufactured by Kikusui Seisakusho Ltd.). A tablet having a weight of 200 mg, a diameter of 8 mm, and 12 R was prepared under a compression force of 5 kN with a gravity feeder at the number of rotations of the turn table of 54 rpm. The physical properties of the resulting tablet are shown in Table 2.

Examples 13 to 22

The operation was performed in the same manner as in Example 12 except that the cellulose powder was changed to Cellulose powders B to K. The physical properties of the resulting tablets are shown in Table 2.

The cellulose powders according to the present invention provided tablets having a hardness of 40 N or more and a friability of 0.5% or less which are suitable for practical use. It turned out that the cellulose powders having an amount of organic carbon derived from residual impurities of 0.09 to 0.15% have an effect of enhancing an aroma and can suppress bad odors.

Comparative Examples 7 to 12

The operation was performed in the same manner as in Example 12 except that the cellulose powder was changed to Cellulose powders L to Q. The physical properties of the resulting tablets are shown in Table 2.

The tablets in Comparative Examples had hardness and friability inferior to those of the tablets containing the cellulose powder according to the present invention. The cellulose powders in Comparative Examples did not suppress odors more significantly than the cellulose powder according to the present invention did. Cellulose powders O to Q masked odors but only weakened the odors probably because the amount of organic carbon derived from residual impurities was significantly larger. Accordingly, Cellulose powders O to Q had no effect of improving odors.

TABLE 2 Direct compressed tablet Amount of total organic carbon (%) derived from Tensile Odor Swelling rate of residual Cellulose Hardness strength Friability sensory tablet diameter impurities in powder (N) (MPa) (%) test (%) tablet residues Example 12 A 85 2.6 0.19 4 1.5 0.144 13 B 76 2.4 0.25 5 1.7 0.131 14 C 67 2.1 0.41 5 1.8 0.115 15 D 55 1.4 0.45 4 2.5 0.090 16 E 52 1.3 0.47 3 2.7 0.085 17 F 51 1.3 0.49 3 2 0.081 18 G 92 2.9 0.11 3 1.2 0.152 19 H 100 3.1 0.08 3 0.9 0.164 20 I 125 3.9 0.04 2 0.7 0.292 21 J 74 2.3 0.31 3 1.6 0.159 22 K 90 2.8 0.15 2 1.3 0.248 Comparative 7 L 39 1.2 0.65 3 3.4 0.068 Example 8 M 31 1.0 0.80 3 3.4 0.062 9 N 29 0.9 1.01 3 3.4 0.062 10 O 38 1.2 0.71 0 3.5 0.331 11 P 30 0.9 0.98 0 4.1 0.420 12 Q 35 1.1 0.62 0 3.5 0.340

Example 23

1120 g of Bofutsushosan Extract-F (manufactured by Alps Pharmaceutical Industry Co., Ltd.), 400 g of Cellulose powder A, and 80 g of a pregelatinized starch “Swelstar” PD-1 (manufactured by Asahi Kasei Chemicals Corporation) were place in a vertical granulator (VG-10, manufactured by Powrex Corporation). While the mixture was stirred (impeller: 280 rpm, cross screw: 3000 rpm), 200 g of an aqueous solution of 6% HPC-L was added, and the mixture was kneaded for 3 minutes to prepare granules prepared by granulation. After the granules prepared by granulation were dried, the granules were sieved with a 1410 μm sieve to prepare granules for pressing. 10 g of vegetable magnesium stearate (TAIHEI CHEMICAL INDUSTRIAL CO., LTD.) was added to 1000 g of the granules for pressing, and was mixed therewith in a plastic bag for 30 seconds. The mixture was pressed with a rotary presser (“Clean Press Correct 12HUK” (trade name), manufactured by Kikusui Seisakusho Ltd.) (tableting pressure: 10 kN, weight: 380 mg, diameter: 9.5 mm, open feeder, the number of rotations of the turn table: 54 rpm). The physical properties of the resulting tablet are shown in Table 3.

Examples 24 to 30

The same operation was performed as in Example 23 except that the cellulose powder was changed to Cellulose powders B to H, and the amount of the aqueous solution of 6% HPC-L was changed to 180 g in Cellulose powder B, 170 g in Cellulose powder C, 120 g in Cellulose powder D, 120 g in Cellulose powder E, 120 g in Cellulose powder F, and 200 g in Cellulose powder G, and 220 g in Cellulose powder H. The physical properties of the resulting tablet are shown in Table 3.

Comparative Examples 13 to 15

The same operation was performed as in Example 23 except that the cellulose powder was changed to Cellulose powders L to N, and the amount of the aqueous solution of 6%

HPC-L was changed to 170 g in Cellulose powder L, 120 g in Cellulose powder M, 120 g in Cellulose powder N. The physical properties of the resulting tablets are shown in Table 3.

The tablets in Comparative Examples had hardness and friability inferior to those of the tablets containing the cellulose powder according to the present invention. The cellulose powders in Comparative Examples did not suppress odors more significantly than the cellulose powder according to the present invention did. Cellulose powders G and H masked odors but only weakened the odors probably because the amount of organic carbon derived from residual impurities was slightly larger. Accordingly, Cellulose powders G and H had no effect of improving odors.

TABLE 3 Tablet by wet granulation method Hard- Tensile Odor Cellulose ness strength Friability sensory powder (N) (MPa) (%) test Example 23 A 101 1.5 0.21 4 24 B 92 1.6 0.30 5 25 C 82 1.4 0.35 5 26 D 71 1.2 0.39 4 27 E 65 1.1 0.41 3 28 F 60 1.0 0.45 3 29 G 115 2.0 0.09 0 30 H 136 2.3 0.06 0 Comparative 13 L 48 0.8 0.54 3 Example 14 M 43 0.7 0.80 3 15 N 32 0.5 1.51 3

Example 31

A placebo tablet (microcrystalline cellulose/lactose=50/50, % by weight, diameter: 8 mm, 12 R, 200 mg tablet) was coated with 50% by weight of sugar relative to the tablet. In the sugar coating, a spraying solution composed of 780 g of talc (average particle size: 5 μm), 20 g of gum arabic, and 200 g of Cellulose powder A was used to form a sugar coating for spraying. While a pan was rotated, an aqueous solution of sucrose was extended onto the placebo tablet. The spraying solution was then added, was extended, and was dried with about 60° C. hot air for 10 minutes. This operation was repeated to form 50% by weight of sugar coating layer relative to the placebo tablet. The physical properties of the resulting tablet are shown in Table 4.

Examples 32 to 38

The operation was performed in the same manner as in Example 31 except that the cellulose powder was changed to Cellulose powders B to H. The physical properties of the resulting tablets are shown in Table 4.

Comparative Examples 16 to 18

The operation was performed in the same manner as in Example 31 except that the cellulose powder was changed to Cellulose powders L to M. The physical properties of the resulting tablets are shown in Table 4.

Among the cellulose powders according to the present invention, Cellulose powders A to D having an amount of organic carbon derived from residual impurities of 0.09 to 0.15% had a whiteness of 95% or more and excellent gloss.

TABLE 4 Sugar coated tablets Cellulose Whiteness powder (%) Gloss Example 31 A 97 ◯ 32 B 96 ⊚ 33 C 96 ⊚ 34 D 95 ◯ 35 E 92 Δ 36 F 89 Δ 37 G 93 Δ 38 H 92 Δ Comparative 16 L 92 Δ Example 17 M 90 Δ 18 N 91 Δ

INDUSTRIAL APPLICABILITY

In the cellulose powder according to the present invention, the amount of organic carbon derived from residual impurities extracted from cellulose particles with hot water during hydrolysis is reduced, and the amount of organic carbon derived from impurities remaining inside the cellulose particles after drying is properly increased. As a result, the cellulose powder according to the present invention can improve not only compression compactibility but also flavor release from Kampo medicines or the like and coloring properties of sugar coating layers. 

1. A cellulose powder having an average degree of polymerization of 100 to 350, a weight average particle size of more than 30 um and 250 um or less, an apparent specific volume of 2 to 15 cm³/g, and an amount of organic carbon derived from residual impurities of more than 0.07 and 0.3% or less, the amount of organic carbon derived from residual impurities being defined by the expression: amount of total organic carbon (%) during extraction with aqueous solution of 1% NaOH−amount of total organic carbon (%) during extraction with pure water.
 2. The cellulose powder according to claim 1, wherein the apparent specific volume is 2 to 6 cm³/g.
 3. The cellulose powder according to claim 1, wherein the apparent specific volume is 2 cm³/g or more and less than 4 cm³/g.
 4. The cellulose powder according to any one of claims 1 to 3, wherein an intraparticle pore volume is 0.1 cm³/g or more and less than 0.265 cm³/g.
 5. The cellulose powder according to claim 1, wherein a water absorption capacity is 1.8 to 4.0 cm³/g.
 6. A molded article, comprising a cellulose powder according to any one of claims 1 to
 5. 7. The molded article according to claim 6, wherein the molded article contains one or more active ingredients.
 8. A method of preparing a cellulose powder, comprising: hydrolyzing a natural cellulose substance at a hydrochloric acid concentration of 0.05 to 0.3% at a hydrolysis temperature of 80 to 150° C. for a hydrolysis time of 40 to 150 minutes to control a volume average particle size of particles in a cellulose dispersion liquid after the hydrolysis to be 70 to 200 μm, and then spray drying the resulting dispersion liquid to prepare a cellulose powder having an average degree of polymerization of 100 to 350, a weight average particle size of more than 30 μm and 250 μm or less, an apparent specific volume of 2 to 15 cm³/g, and an amount of organic carbon derived from residual impurities of more than 0.07 and 0.3% or less, the amount of organic carbon derived from residual impurities being defined by the expression: amount of total organic carbon (%) during extraction with aqueous solution of 1% NaOH−amount of total organic carbon (%) during extraction with pure water.
 9. A molded article comprising one or more active ingredients, one or more additives selected from saccharides, sugar alcohols, starches, and disintegrating agents, and a cellulose powder, wherein the molded article has a hardness of 50 to 200 N, a tensile strength of 0.1 to 12 MPa, a friability of 0 to 0.5%, a swelling rate of a diameter of the molded article in acetone of 0 to 3.3% or less.
 10. The molded article according to claim 9, comprising 5 to 90% by weight of a cellulose powder.
 11. The molded article according to claim 9 or 10, wherein an amount of total organic carbon derived from residual impurities in molded article residues obtained through washing of the molded article with acetone, ethanol, pure water, and ethanol sequentially and extraction is more than 0.07 and 0.3% or less.
 12. The molded article according to claim 9 or 10, wherein an amount of total organic carbon derived from residual impurities in the cellulose powder obtained through washing of the molded article with acetone, ethanol, pure water, and ethanol sequentially and extraction is more than 0.07 and [[is]] 0.3% or less. 